4-transistors of dynamic memristor based tcam

Nilesh Mishra, Harish M Kittur / International Journal of Engineering Research and Applications

(IJERA) ISSN: 2248-9622 www.ijera.com

Vol. 2, Issue 3, May-Jun 2012, pp.2520-2524

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4-Transistors of Dynamic Memristor based TCAM Nilesh Mishra Harish M Kittur

M.Tech VLSI Design M.Tech VLSI Design

School of Electronics Engineering School of Electronics Engineering

VIT UNIVERSITY,Vellore,INDIA VIT UNIVERSITY,Vellore,INDIA

Abstract: New hybrid hardware architecture,

which compatible to CMOS technology also

important role in a network like internet of fast

searching of data. Here an explored new idea of

CAM (content addressable Memory) with

implemented emerging technology of Memristor.

Great advantage of memristor, its nonvolatile,

retention time of data stored at longer period In

Dynamic 4 NMOS transistor used to describe

about idea of CAM with memristor. Cell is assets

of two things storing and matching with three

elements required, hence terms comes ternary. It

has three states is zero (0), one (1) and don’t care

condition (x). Circuits simulations show that all

basics operations read, write and match at good

speed. We proposed new dynamic hybrid TCAM

cell good optimization of retention time and high

speed search data.

Keywords Memristor, CAM(content addressable

memory), Modeling , SPICE, Window function, drift.

TCAM

1. Introduction In this paper new conceptualization of design and

modeling of a Memristor based content addressable

Memory (CAM) of architecture design and modeling.

A typical base conventional content addressable

Memory cell of SRAM that has 2 n-type and 2 p-type

MOS transistors which requires both VDD and GND

connections of well-plugs within each cell[2]. But

also volatile, data is lost when memory is not

powered. Here memristor technology, which has

non-volatile memory (NVM) behavior and can be

fabricated as an extension to a CMOS process

technology with nanoscale geometry. In this single

CAM only 4-NMOS transistors and 2-Mermristors is

used. Main important data is never lost inside a

memristor, if the powered is switch off also search

line in this novel CAM inside. The main principle

behind to stored and compared data it is allows data

in parallel to be comparison. Therefore, fast speed

search the data. if input data match to stored data

indicated that data should be match. The application

of CAM in major network side and pattern matching

here main focus on Ternary CAM widely used in

routers at routing table to compare destination

address also memristor is work like switch, much

similar to transistor but parameter view it has two

terminal rather than three. The physics principle

behind in memristor mobile ionic charge transfer one

state to another state vice versa. This paper

innovation new idea of architecture CAM of fast

search good retention time without lost data.

2. Nonlinear behavior of memristor First prediction in 1978 theoretical of memristor in

missing circuit paper by professor Chua [1] then later

on 2008 first prototype memristor made in HP Lab

[6]. The two layers of thin films one is doped region

TiO2-X another is undoped TiO2 and sandwich

between platinum is connected. Diameter (D=10nm)

approx, which consist oxygen vacancies on doping

side when voltage has given on doped area the

mobile ionic charge of oxygen depleted on undoped

region also resistance of both side should variable

depend upon voltage. Such type characteristics has

been done by using spice model by taken joglekar

window function[8].

fig(1) Memristor Model in HP lab

D – diameter of thin film,

w- width of doped region

P- parameter of window function

µV- Migration coefficient

RON/ROFF – Resistance ON/OFF States

RINIT Resistance of T=0

Nilesh Mishra, Harish M Kittur / International Journal of Engineering Research and

Applications (IJERA) ISSN: 2248-9622 www.ijera.com


2521 | P a g e

fig(2) Window function, different „p‟value

fig(2) is window function depend upon by „p‟

integer, if increase „p‟ value disappear nonlinear

drift.

Here ohm‟s law applicable in Memristor between

voltage and current fig(1)

V (t) = RMEM (w) I (t)

Variable and transfer the resistance from doped to

undoped region depend upon current passed through

Memristor.

Sum of resistance of RMEM in doped and undoped

region.

RMEM = RON(X)+ROFF(1-X)

The proposed window function is a

following term fig(2)

Characterization of memristor in a form

such manner to regulated in HP Lab in

spice tools, here implementing of MCAM (Memristor

based content addressable memory) Embodiment of

TCAM to more efficiency and less power drop ,and

high searching speed.

3. SPICE Modeling of Memristor based

TCAM Here used pass transistor of NMOS for made

proposed MCAM (Memristor based CAM). They are

4 NMOS only used stored data and compared here

below schematic diagram in fig (3) . Parameter

mention write condition (Twa,Twb), data is stored in

a (Tsa,Tsb) memristor here if compared data, its

worked like XOR by (Tca,Tcb), Retrieved data

Voltage has been given (MVL) , Which passed

through (U1,U2) of Memristor. Stored data comes

outside for start to matched. Now if data pass through

(S1,S-bar) then inside data already present in a

(Tca,Tcb) which comes from memristor to start

matched. If data should be match line does not

discharged vice versa

Fig(3) 4-T DCAM with Memristor

Table1: match operation

Here above table ternary cam operation has been

done there is match condition its only created. When

the (U1,U2) memristor and search line should be 1

or 0 . There is X dont care condition which can

resembale to be operated fast search the data in

ternary cam. Also XOR Tca and Tcb is word

compared data between search line and memristor

(U1,U2). The proposed Dynamic CAM cell needed

refresh cycle during read and write operation[3].

Stored Tsa

memristor(U1)

Tsb

memristor(U2)

S(search

line)

S0(search

bar line)

Match

condition

0 0 1 0 1 Match

0 0 1 1 0 No match

1 1 0 1 0 Match

1 1 0 0 1 No

Match

X 0 0 X X Match




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4. Read and Write Operations Simple basic operation of write condition

(Twa,Twb) of Transistors is can be done by logic

„1.‟ Here pointed out the write condition take place

all the same row also that time match line should be

kept as floating, Tpch and Trd are off. In memristor

of U1 and U2 data is saved during write time at that

time do not need refresh only simple write and

saved data is present. Memristor is very prominent

data saved long duration time. And (S,S0) input

address search line will be off on write

conditionRead time of MVL(Memristor Voltage

line ) would be activated, so in such case memristor

in data is retrived passed through transistor

(Tca,Tcb). Here compared data between search data

(S,S0) and Transistor (Tca,Tcb), if both data should

be match then data should not be discharged. If

does not match then it is discharaged. In

convational CAM, search line located in outside.

But in this proposed CAM search line are inside In

fig(5) during read operation its necessary

BIT,NBIT and match line precharge must be one.

Once‟s precharged is activated Trd line is high then

match line drawn to ground state. So ternary CAM,

its followed don‟t care condition, whatever data

present in BIT,NBIT line latched also (Tca,Tcb)

equal to „0‟ and line is not to be discharged.

Fig(a) precharge and read lines

In fig(4) 2×2 MCAM architecture by suggested

Matchline1 condition, Here data is search(1,0), In

fig(c) waveform green is MVL and yellow is a

Match line. “The first row cells are programmed

“10”. As the consequence, ML is discharged since

there is a match between the stored and search bit

for mention ML is output

RESULT Simulation circuit based on following

parameters [9] Ron = 100Ω, Roff = 100kΩ, D =

10nm, P = 5,µv = 3×10-8

m2/s/V it can be

impleme0.18technology

Table2: Power TCAM and Memristor

Fig(b) 2x2 HybridTCAM

fig(c) 2x2 TCAM wave form Analysis

Dynamic MCAM Power (Memristor) Total Power

4T 36.2µW 409.4µW




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5. Waveform Analysis

Fig(a)

fig(b)

Fig(c)

Fig(d)

Fig (e)

Fig (5)

Search line S in 3Volt during match condition at Matching line fig (a) read, write and match in 3 volt fig (b)

40µA current passed U1memristor(e), Indicated 1.2 voltage and frequency 1Hz (d) , Hystresis curve volgate

versus current in Memristor(c)

6. SPICE code of TCAM with Memristor:-




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Conclusion In this paper presented novel dynamic hybrid based

TCAM only utilizes 4T-NMOS. Here we can flash

a made new technology in future, which challenge

scaling CMOS technology below 15nm of

nanoscale. Memristor strong innovate device for

terabit/compare logic. Main important factor data is

never lost of many years if power is lost. In future

hope new trend to design of TCAM with memristor

which emphasize electronic circuits

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eleme element, IEEE Trans

circuit Theory, vol. CT-18. No.

5,pp.507519,Sep.1971

[2] N. Weste and K. Eshraghian, PrincipZes of

CMOS VLSI Design -A Systems Perspective,

Second Ad- dition, Reading, MA: Addison-

Wesley, pp. 589 -590, 1993.

[3] J. P. Wade and C. G. Sodini, “Dynamic cross-

coupled Bit-Line Content Addressable Memory

cell For High-Density Arrays,” IEEE Journal

of Solid-State Circuits, Vol. 22, No. 1, pp. 119-

121, February 1987.

[4] STRUKOV, D.B., SNIDER, G.S., STEWART,

D.R., WILLIAMS, R.S. The missing

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[5] CHUA, L.O. Memristor – the missing circuit

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[6] WILLIAMS, R. S. Electrically actuated switch.

United States Patent Application 20

080090337, 04/17/2008.

[6] WILLIAMS, R. S. How we found the missing

memristor. IEEE Spectrum, 12/01/2008, p. 1-

11, www.spectrum.ieee.org/print/7024.

[7] JOGLEKAR, Y.N., WOLF, S. J. The elusive

memristor: properties of basic electrical

circuits. arXiv:0807.3994 v2 [cond-

mat.meshall] 13 January 2009, p.1-24.

[8] WANG, F.Y. Memristor for introductory

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ph], 4 August 2008, p.1-4..

[9] K. Witrisal. Memristor-based stored-reference

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4-transistors of dynamic memristor based tcam

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